Current parallel graphics data processing includes systems and methods developed to perform specific operations on graphics data such as, for example, linear interpolation, tessellation, rasterization, texture mapping, depth testing, etc. Traditionally, graphics processors used fixed function computational units to process graphics data; however, more recently, portions of graphics processors have been made programmable, enabling such processors to support a wider variety of operations for processing vertex and fragment data.
As part of the graphic data processing, images to be displayed to a user are generated by rendering graphical objects into the output images. Current approaches may use a high resolution image buffer into which all of the graphical objects are rendered. This approach may require significant amounts of computations to be performed at the highest image resolution even though not all objects in the 3D scene are of the same importance to the viewer.